Note: There are also many herbs of the same family which are
called mustard, and have more or less of the flavor of
the true mustard; as, bowyer's mustard ({Lepidium
ruderale}); hedge mustard ({Sisymbrium officinale});
Mithridate mustard ({Thlaspi arvense}); tower mustard
({Arabis perfoliata}); treacle mustard ({Erysimum
cheiranthoides}).
[1913 Webster]